This invention is in the field of eyewear, and more particularly in the field of eyewear for stereoscopic or three-dimensional visualization.
Because the eyes of humans are in different positions on the head, they perceive slightly different views. This is the basis of stereopsis, the process by which the brain exploits the parallax due to the different views from the eye to gain different perception and estimate the distance to objects. Based on the same principle, parallax has been exploited in the engineering of devices for stereoscopic visualization.
A common method for producing stereoscopic images for a viewer is to project two sets of images, wherein the projected images are filtered such that one set of images is linearly polarized in a first direction, and the second set of images is linearly polarized in a direction perpendicular to the first direction. The two sets of images are stereoscopic, i.e., imaging the same view from slightly different positions. The images are viewed by a viewer through a pair of spectacles having polarizer (or polarized) lenses, wherein the polarization direction of the lenses are offset by about ninety degrees. The polarization directions of the projected images are similarly oriented, so that each lens is substantially transparent to one set of images, and is substantially opaque to the other set. The user's left eye, therefore, sees the first set of images, and the right eyes sees the second set of images. Using parallax, the viewer is able to perceive a stereoscopic image assembled from the left eye image and the right eye image, providing an illusion of three-dimensionality. Examples of stereoscopic imaging apparatus taking advantage of polarization are disclosed, for example, in U.S. Pat. No. 3,975,474, and in U.S. Pat. No. 7,164,529, both of which are incorporated by reference in their entirety.
However, current stereoscopic viewing technology usually requires the use of bulky devices such as 3D viewing glasses, which are often inconvenient for a viewer to carry around and keep track of. In addition, the current external stereoscopic viewing devices, such as glasses, limit the mobility of the viewer and, therefore, do not allow a complete experience in a virtual world. The present invention seeks to overcome the disadvantages of current stereoscopic visualization devices and provides further related advantages.